Much work has been done over the years in the field of heterogeneous catalysis. Such catalysts have experienced enormous commercial success in many chemical processes, particularly petroleum and petrochemical process applications. Conventional heterogeneous catalysts are typically comprised of one or more catalytically active metals, particularly Group VIII and Group VI metals on an inorganic support. The inorganic support is typically a metal oxide such as alumina, silica, alumina-silica, titania, magnesia, as well as molecular sieves. Various forms of carbon have also been suggested as being suitable as catalyst support materials. For example, U.S. Pat. Nos. 5,538,929 and 6,277,780 teach the use of a phosphorus treated activated carbon as catalyst supports. Also, U.S. Pat. No. 5,972,525 teaches solid particles comprised of carbon and metal oxides as being suitable catalyst supports. While most of the art teaches the use of conventional carbon, such as activated carbon as catalyst supports, two patents, U.S. Pat. Nos. 5,569,635 and 6,159,892 disclose the use of nano-size cylindrical carbon “fibrils” as catalyst supports. Various catalytically active metals, preferably noble and non-noble Group VIII metals, such as Fe and Pt, are deposited onto the fibril support material. Metal oxides, such as Fe2O3 can also act as a catalyst when deposited onto the carbon fibrils.
While it has been known for many years that both macro and nano-size carbon particles are suitable support materials for certain types of catalysts, it has not been known that certain types of graphitic nanofibers have unique and unexpected catalytic properties themselves, without the addition of a catalytically active metal. In co-pending application, U.S. Ser. No. 10/712,247, it is disclosed that graphitic nanofibers comprised of a plurality of graphite sheets aligned in directions parallel, perpendicular, or at an angle to the longitudinal axis of the nanofiber are suitable for catalyzing a variety of chemical reactions. It has unexpectedly been found by the inventors hereof that if the graphite nanofibers in which the graphite sheets are oriented perpendicular, or at an angle, to the longitudinal axis are initially treated at high temperatures then their subsequent catalytic performance is unexpectedly enhanced over that of the corresponding untreated materials.